TrueNAS is an open source project to create an appliance package to turn a computer into a Network Attached Storage. Originally based on the FreeBSD operating system, it appears they are slowly moving to Linux. TrueNAS is offered as a free public version, or you can get excellent support with their fully supported Commercial version.

TrueNAS can be installed on consumer grade hardware and server grade hardware, including hardware specifically designed for TrueNAS available from iXsystems (the company that develops TrueNAS).

We use TrueNAS for a stable system that allows our customers to do basic management without the need to drop down to the command line.